This adventure is truly epic in scale.
It's a war, with heroes, troops, vehicles (airships and alien tripods!), some political ramifications, glory and salvation.
There's a useful flowchart in the back of the adventure, where the variety outcomes of the battles and decisions will still lead to the final showdown. I'm guessing that there's plenty of hours of play here. Definitely for veteran players who'd like to branch out into mass combat - so make sure you own the extra rules needed to play (read the product description carefully).
Summary: Exotic 40K with a decent plot. ;)